This invention pertains to fuel cell stacks and, in particular, to gas cooler assemblies used in such stacks.
In the construction of fuel cell stacks, it is typical to provide a system for cooling the fuel cells of the stack. U.S. Pat. No. 4,192,906, assigned to the same assignee hereof, teaches a fuel cell stack comprising a gas cooling system which includes plate structure supported within the stack and having passages for carrying a cooling gas. This plate structure is situated in the stack so as to be electrically in series with its adjacent fuel cells. As a result, it must exhibit good electrical conductivity, at least in its interior regions, these regions serving to couple electrical energy between the adjacent cells. The plate structure also, of course, must exhibit good thermal conductivity so as to provide the necessary cell cooling.
As above-noted, the above plate structure is supported within the fuel cell stack to form the cooling system. The plate structure, therefore, is not in the form of an integral cooler assembly which itself can be handled as a commercial unit and removed or installed in the stack as desired. As a result, considerable research has been carried out to devise practices for forming the plate structure as an integral commercial unit.
In one practice, graphite-resin material, owing to its high electrical and thermal conductivities, its acid resistance and its moldability, is used to form each cooler assembly. Difficulties have been encountered, however, in attempting to form the assembly from a single plate. Thus two plates are typically used, these plates being joined together by bonding. Such practice further contemplates realizing an improved integral gas cooler assembly by carbonizing the plate resin material through heating the plates prior to bonding.
It is an object of the present invention to provide an integral gas cooler assembly having improved characteristics.
It is a further object of the present invention to provide an integral gas cooler assembly having improved electrical conductivity and strength.